Stable diazo material



Patented Apr. 8, 1947 STABLE DIAZO MATERIAL Jonas John Ch'echak, Rochester, N. Y, assig'nor to Eastman Kodak Company, Rochester, N. Y., a corporation-of New Jersey N Drawing.

ifllaims. 1:

This invention relatesto sensitive diazotype material.

In diazotype material adiazonium salt is generally incorporated in the sensitive layer and an image is formed by decomposing the diazonium salt by the action of the'light and coupling the diazonium salt at the residual unexposed portions of the layer with a: diazo coupler to form a dye image. The diazonium salts incorporated in the sensitive material are known to be unstable and hi ls customary'to include a. stabilizing agent such as a weak acid in the sensitive materiall It is an object of the present invention to provide diazotype. materials in which the sensitive compound has greater stability than the diazonium salts customarily employed. A further object: isto provide a; novel type of sensitive diazo material; Other objectswill appear from the fOIIOWiIlg description of my invention.

These objects are accomplished by using as the light sensitive diazo materiala diazobiguanide; that is, a compound formed by the reaction of a diazonium salt with biguanide or a derivative of biguanid'e;

I have found that the diazobiguanides are more stable than the diazonium salts from which they are formed and. that the diazobiguanides are i sensitive to light and may be used in a photo-'- graphic layer for the formation of a dye image. The portions of a sensitivelayer containing a diazobiguanide which are acted upon by light are rendered-incapable of dye formation. This isbecause the action of light is to destroy the azo bond of-thediazobiguanide so that the compound is: no longer capable of coupling. This action is believed to be similar to the action of light upon the usual diazo-nium compound to destroy its coupling ability. In the unexposed regions of the layer containing the diazonium biguanide the sensitive compound is unaffected and upon treatin the layer With heat and moisture in the presence of a diazo coupler, the diazonium salt is released from the diazobiguanide and immediately couples with the diazo coupler to form a dye image. The presence of a weak acid such as citric acid aids in the splitting of the diazobi- Biguanide itself may be used in forming the diazobiguanides, or various substituted biguanides Application November 16, 1944, Serial No. 563,790

may be employed. The biguanide" may" have alkyl', aralkyl, aryl, hydroaryl, orheterocyolic'sub stituents aslong as these substituents are not themselves capable of coupling With the diazo' compounds. B'iguanides which I may use" includel-methylbiguanide, l-ethylbiguanide, l-phenylbiguanide, l-benzylbiguanide, l-m-phenylbi'guahide sulfonic acid and c-naphthylbiguanid'e and its homologs.

The biguanides may be coupled with any diazotized amine such as aniline, t'oluidine"; 2,5-di chloroaniline, 2-methyl-5 chloroaniline, Z HlBbh ylaniline, 5=chloroaniline, 2-metl'iyl-4-nitroaniline, 3-nitrol-chloroaniline; orthoanisidine, 2- methoxy 5-methylaniline, z-aminodiphenyl'ether; 2-methoxy-4 chloro=-5 methy1'-ani1ine,' 5-benzoylamino-2,5-diethoxyaniline; 4-amino-2 methylsulfonamido-e-dimethylamihoazobenzene.

The diazobiguanides may be" prepared as do scribed in Lecher U. S, Patent 2,125,509.

In the preparation of the diazobiguani'des for use in my process I prefer to use diazonium salts which do not contain an acid group such: as sulfonicacid or'carboxylic'acid; If such acid groups are present there is likelihood of forming a salt with the biguanide instead of forming the diazobiguanide. r

In the preparation of a printing'material coritai'riing the diazobiguanides, a support of paper or other suitable material is coated with a solution of the diazobi'guanide. The di'azo coupler may also be incorporated in the coating or'the coupler may be applied by. immersing the exposed material in a solution containing it. It will be understood that any suitable diazo coupler may be employed, these compounds generally being phenolic or naphthoic couplers, or active methylene compounds such as phenol, fi-naphthol, 2-hydroxy-3-naphthoic acid, or acetoacetanilide.

It is necessary that moisture be present in developing the dye image in the exposed material, and in order to satisfy this requirement the material may be developed with steam or by im-. mersion in water, or a hygroscopic agent may be incorporated in the coating prior to exposure so that the necessary amount of moisture is retained in the coating, and in this case the exposed material can be developed simply by placing it in an oven or on a hot surface.

The following examples illustrate the formation of colored images according to my invention:

Example 1 Paper was coated with 10 cc. of a commercial denatured ethyl alcohol (Formula 3A) solution containing 0.1 gram of the diazobiguanide made from diazotized 4-benzoylamino-2,5-diethoxyaniline and the biguanide of metanilic acid, and 0.5 gram of 2-hydroxy-3-naphthoic acid. The diazo biguanide used as the sensitive material in this coating is believed to have the following formula:

CgHs H The coating was dried and was then exposed to 7 light behind a step wedge and developed by treatment with steam. A blue dye positive image was obtained. The development is considerably faster if the steam contains acetic or formic acid vapors.

Example 2 Paper was coated with 10 cc. of an-aqueous solution containing 0.2 gram of the diazobiguanide made from diazotized a-amino-z-methylsulfonamid0-4-dimethylaminoazobenzene and biguanide and 0.8 gram of ,c-naphthol. The diazobiguanide used as the sensitive material is believed to have the following formula:

and is exposed and processed as in Example 1. A blue positive image was obtained.

An acid such as citric acid may be incorporated in. the sensitive material to promote the splitting Example 3 Paper was coated with a solution of 0.1 gram of the diazobiguanide from diazotized e-benzoylamino-2,5-diethoxyaniline and the biguanide from metanilic acid, 0.5 gram 2-hydroxy-3-naphthoic acid and 0.5 gram formamide in 10 cc. ethyl alcohol (Formula 3A).

' Upon exposure the paper is developed b dry heat as in an oven or on a hot plate or roller.

Example 4 Same as Example 3 except that citric acid is used in place of the formamide and steam is 4 required for development to supply moisture as well as heat.

.The examples and modifications included herein are illustrative only and various diazobiguanides and diazo couplers may be employed in my process. A wide range of colors may be obtained and a mixture of diazobiguanides may be used to yield a black image. The diazobiguanides are stable in the coating and at the same time retain their light sensitivity.

It will be understood that my invention is to be taken as limited only by the scope of the appended claims.

I claim:

1. The method of forming an azo dye image in a light-sensitive layer containing a stable diazobiguanide and a diaz'o coupler, which comprises exposing said layer to light rays in the form of an image to decompose the azo bond of the diazobiguanide in the exposed portions of the layer, and heating the layer in the presence of moisture to split the diazo biguanide in the residual por: tions of the layer and cause it to couple with the diazo coupler.

2. A light-sensitive photographic element comprising a paper support-having thereon a stable sensitive aromatic diazobiguanide, a diazo coupler and an acid former selected from the group consisting of formamide and triacetin.

3. A light-sensitive photographic element comprising a paper support having thereon a stable sensitive'aromatic diazobiguanide, a diazo coupler and an acid selected from the group consist ing of citric and tartaric acid.

4. The method of forming an azo dye image in a light-sensitive'layer containing a stable diazobiguanide, which comprises exposing said layer to light rays in the form of an image to decompose the azo bond of the diazobiguanide in the exposed portions of the layer, and heating the layer in the presence of moisture and a diazo coupler, to split the diazo biguamde in the re sidual portions of the layer and cause it to couple with the diazo coupler.

JONAS JOHN CHECHAK.

REFERENCES CITED The following references are of record in the file of this patent:

UNI'ITED STATES PATENTS Number McClellan et al J 25, 1944; 

